Fix duplicate Additional CSS classes post author, etc.

[shimotmk]

What?

Fix duplicate Additional CSS classes

Why?

Duplicate class names when using custom classes
I don't think it's necessary to add a custom class in each block since it's added with get_block_wrapper_attributes.
https://developer.wordpress.org/reference/functions/get_block_wrapper_attributes/

How?

Testing Instructions

1. Open a Post or Page.
2. Insert a Heading post author Block.
3. Set Additional CSS class
4. Look at the class name on the publish screen.

Screenshots or screencast

Movie

movie.mov

Before

After

Site logo, social icon also had duplicated class names, but they were included in this branch, is it OK to include them in this branch?

[github-actions]

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[Mamaduka]

The fix works as expected. Thanks for contributing, @shimotmk.